This is the military issue Buttstock Cleaning System for all 5.56MM rifles. Containing bright brass finished components, the Buttstock Cleaning System is specifically designed to clean and maintain the M4, M16, M249, and Mod 46. Flexible cleaning rods quickly clean the receiver, chamber, neck and bore; obstruction removers knock out bore obstructions and stuck cases. All purpose brushes and comprehensive instruction booklet maintain flawless performance in mission critical situations.